# Relationship history for MSHA mine 4001833

Current hierarchy: **Morris James F → Hard Rock Coal Company → Hard Rock Mine**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Hard Rock Coal Company → Hard Rock Mine; 1975-09-04 to 1976-03-10; source msha-controller-operator-history
- **controller_controls_mine:** Vaughn Ross → Hard Rock Mine; 1975-09-04 to 1976-03-10; source msha-controller-operator-history
- **controller_controls_operator:** Vaughn Ross → Hard Rock Coal Company; 1975-09-04 to 1976-03-10; source msha-controller-operator-history
- **operator_operates_mine:** Hard Rock Coal Company → Hard Rock Mine; 1976-03-11 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Morris James F → Hard Rock Mine; 1976-03-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Morris James F → Hard Rock Coal Company; 1976-03-11 to current/open; source msha-controller-operator-history